I understand what you're saying, but that's not an issue here. This is someone I trust and whenever he doesn't know the answer he is the first to say so. In this instance when I told him about better accuracy with lighter loads, he said he has experienced something similar. I realize that this is all anecdotal and is in no way definitive, but it does tell me that my experience isn't unique.

That said, I have more questions here. Would I be correct to assume that a heavier buffer will give more consistency in the cycling of the bolt carrier and more consistency in the muzzle velocity? Being that my rifle at this point appears to prefer lighter loads would I get a short stroking again if I went with too heavy of a buffer? In a carbine system, how much difference in accuracy could I even expect from a different buffer?

I have no idea what you could expect, you will gain consistency and reliability.